AB1455 VERY LOW FREQUENCY ANAS/DFS70 PATTERN POSITIVITY IN A LARGE COHORT OF AUTOIMMUNE/AUTOINFLAMMATORY AND CONTROLS IN A SINGLE HOSPITAL FROM COLOMBIA
Authors: C. Romero-Sánchez, O. J. Calixto, V. S. Romero Alvarez, A. Vargas, L. Castro, J. Amador, P. Lopez-Mojica, D. Marin, D. Acero-M., M. Acevedo-Godoy, D. Rincon-Riaño, W. Bautista-Molano, J. M. Bello-Gualtero
Journal: Annals of the Rheumatic Diseases (2022)

Background Antinuclear antibodies (ANA) have diagnostic significance in rheumatology. Anti-DFS70 (Dense Fine Speckle-70 kd) antibodies may be an exclusionary marker for systemic autoimmune rheumatic disease (SARD). Low frequency of this pattern has previously been described in healthy populations. Objectives To evaluate ANAS/DFS70 positivity and autoantibody profile in a large Colombian population with rheumatoid arthritis (RA), psoriasis (PsO), as well as, undifferentiated connective tissue diseases (UCTD), first degree relatives (FDR), and healthy controls (HC). Methods A cross-sectional study was conducted. We analyzed 531 individuals between 18-65 years, 101 RA patients (ACR/EULAR 2010 classification criteria), 137 relatives from RA, 60 PsO patients (Colombian classification consensus), 47 UCTD patients, and 186 HC matched by age and sex. The determination of ANAS-HEp2 antibodies, was carried out. The ANAS/DFS70 positive results used as a confirmatory test the determination by Knocked out, for the psip gen and CytoBead by indirect immunofluorescence-IFI technique. Absolute and relative frequencies were established and associations with chi square test. Results The distribution by diagnostic group was RA: 19%, PsO: 11,3%, UCTD: 8,9%, 25,8% RA relatives, and 35% healthy controls. RA was ANA test (+) in 42%, PsO 41,7%, UCTD 78,7%, FDR 26,3%, and HC 26,9%. The positive frequency of ANA/DFS70 in the total group was 2.3% and 1,4% in SARD (n=12; 2 FDR, 6 HC, 3 UCTD, and PsO 1), no RA patients were positive. These 12 participants were negative for rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA), one patient with UCTD were positive for Anti SSB/La, Anti Sm, Anti RNP, and anti DNAds, another was positive for anti Sm IgG and IgM B2GP, and IgG ACA. Most participants had negative acute phase reactants (erythrosedimentation rate ESR[-] 83,3% and C-reactive protein CRP[-] 66,6%). ANAS/DFS70 was associated with positivity for ANAS independently of ANAS titers, (p &lt;0,001). None of the patients’ positives ANAS DFS70 in the UCTD group in 5 years developed definitive autoimmune disease. Conclusion Despite the low frequency in the group in general, it has been shown that anti-DFS70 is more prevalent in healthy individuals than in patients with SARD, which was found in this group of individuals. ANAS/DFS70 autoantibodies were present in very low frequency in Colombian patients with SARD. Thus, patients with a positive result tend to have a mild or non-progressing phenotype of autoimmune or autoinflammatory diseases. This analysis reinforce evidence of ANA/DFS70 positivity as well as autoantibody negativity described abroad as a negative predictive marker of SARD. Table 1. Clinical and demographical variables for ANAS/DFS70 patients n=12. AGE GENDER ANAS ESR CRP RF ACPA Ro La Sm RNP DNAds ACA IgG ACA IgM ACA IgA B2GP IgG B2GP IgM UCTD 30 F 1/160 - - - - - - + - - + - - + + UCTD 61 F 1/320 - - - - - + + + + - - - - - UCTD 42 F 1/160 - + - - - - - - + - - - - - PsO 43 F 1/320 - - - - - - - - - - - - - - FDR 31 M 1/80 - - - - - - - - - - - - - - FDR 32 F 1/160 + - - - - - - - - - - - - - HC 50 F 1/80 - - - - - - - - - - - - - - HC 26 F 1/80 + - - - - - - - - - - - - - HC 27 F 1/160 - - - - - - - - - - - - - - HC 54 F 1/320 - - - - - - - - - - - - - - HC 32 F 1/160 - - - - - - - - - - - - - - HC 53 F 1/320 - + - - - - - - - - - - - - Rheumatoid arthritis (RA), Psoriasis (PsO), as well as, Undifferentiated connective tissue diseases (UCTD), first degree relatives (FDR), healthy controls (HC), rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA), erythrosedimentation rate (ESR), and C-reactive protein (CRP). Acknowledgements Hospital Militar Central / Universidad del Bosque Disclosure of Interests None declared